


What Could Have Been

by WriterGreenReads



Series: USS Thanatos [5]
Category: Star Trek, Star Trek: Deep Space Nine, 僕のヒーローアカデミア | Boku no Hero Academia | My Hero Academia
Genre: Alternate Universe - Star Trek Fusion, Angst, Crossovers & Fandom Fusions, Dominion War (Star Trek), One for All is a Trill Symbiont
Language: English
Status: Completed
Published: 2021-03-14
Updated: 2021-03-14
Packaged: 2021-03-22 22:02:31
Rating: Teen And Up Audiences
Warnings: Major Character Death
Chapters: 1
Words: 1,889
Publisher: archiveofourown.org
Story URL: https://archiveofourown.org/works/30045426
Author URL: https://archiveofourown.org/users/WriterGreenReads/pseuds/WriterGreenReads
Summary: How Izuku Midoriya came to serve on the USS Thanatos, and what he lost and gained on the journey.
Relationships: Midoriya Izuku & Yagi Toshinori | All Might
Series: USS Thanatos [5]
Series URL: https://archiveofourown.org/series/2154921
Comments: 4
Kudos: 8





	What Could Have Been

In another universe, Izuku Midoriya lived a long, happy, heroic life. 

In another universe, Izuku Midoriya found a father figure in a man named Toshinori.

In another universe, Toshinori got to see Izuku grow into a fine young man, and supported him every step of the way.

In another universe, Izuku Midoriya wasn’t left alone.

This is not that universe.

* * *

Izuku Midoriya is Trill, and UnJoined. 

That in itself isn’t exactly a rarity on the Trill homeworld. He applied to the Symbiont Program like many other hopefuls, and like so many hopefuls, his application was denied before he could even enter.

It had been Izuku’s dream to be Joined. And with a short, impersonal letter, that dream had vanished.

Starfleet had been the next, logical choice.

This time, he was accepted.

After bidding his mother a very tearful farewell, Izuku moved on to the stars, away from Trill and the painful memories the planet’s pools and wetlands carried with them.

Earth was… an  _ experience. _

The coursework was easier than he’d expected, honestly. And the people were genuinely kind and welcoming. He’d actually made some genuine friends, for maybe the first time in his life. S’Ra, a Caitian who dragged Izuku to the 602 Club more times than he could count with the reasoning of “you need to get out more.” Harry Kim, a human that turned out to be an excellent study mate and ended up introducing Izuku to Earth music. 

And then there was Bakugou Katsuki.

His roommate.

Bakugou was an entirely different experience all of his own.

Izuku had never gotten into so many fights in his  _ life. _

The first year on campus had been incredibly awkward between the two of them, but somehow, by the time final exams rolled around, Izuku realized that he’d had every intention of rooming with the human again next year.

So did Bakugou, apparently.

And from there? Their antagonism became more of a rivalry.

The main issue of said rivalry was that they were both… let us say  _ intense _ personalities. And they were very competitive. Even about being competitive.

Their fights were audible from the other side of campus, as a very unimpressed Vulcan professor had informed them. 

And loudness? Not conducive to study. And so ever since the first month of their time at the Academy, the following sign was hung on the library’s door.

“Until further notice, Cadets Bakugou and Midoriya are not allowed in the campus library at the same time.”

Bakugou and Izuku had both taken one look at the sign, looked back at each other, and promptly sprinted to be first in the door.

(Izuku was first in that day, something that apparently Bakugou took personal issue with.)

And  _ man, _ could that human hold a grudge.

He’d proven it, too, by consistently booking the library for his use only whenever it was  _ most inconvenient  _ for Izuku, like around finals or midterms, or just generally when he wanted to use the library for studying.

However, for their final year at the Academy- Izuku had a  _ plan. _

It took literally a year of planning and a lot of favors (not bribes, bribes were illegal), but he’d managed to reserve space in the library for the entire month leading up to final exams.

And the screams of absolute rage that had carried all the way across campus once Bakugou realized just how outmaneuvered he’d been had been  _ so worth it. _

Before Izuku knew it- it was time to graduate. He and Bakugou were both heading off on paths of their own; Bakugou into security, Izuku into engineering, both on the command track.

Now, Bakugou hadn’t said goodbye or good luck, or anything sappy like that. No, he’d just punched Izuku in the shoulder and grumbled something along the lines of “you better not fucking die out there before I make captain before you.”

Izuku would take it.

So with a black and gold uniform, a shiny new pip on his collar, and a big, if slightly nervous, smile on his face, Izuku took off to space.

His first real assignment.

Izuku was assigned, with the rank of ensign, to Dagobah Station, a medical space station on the outskirts of Federation territory, as an operations technician. 

Yeah… Not exactly the most exciting job.

He  _ had _ decided to take this career path, Izuku reminded himself. This was his choice to be here.

His job was pretty simple- keep the station working, assist the medical officers if need be, and generally make sure Dagobah Station ran smoothly.

He worked most often in Wing 17, the Recovery Wing, and was partnered with the newest doctor on staff, Tsuyu.

Doctor Tsuyu was Denobulan, Lieutenant JG., and a few years older than Izuku. She was pragmatic, blunt, and efficient.

And to Izuku’s  _ great _ surprise, given the anxious and emotional person he was, she decided almost immediately upon meeting him that they were going to be friends.

“I always say what’s on my mind,” she’d calmly said after telling him that, while he spluttered and flailed just a little bit. “And I think we should stick together, Midoriya. Come realign my phase inversion scanner, please.”

So Izuku did.

This was his routine for about a month, until one encounter changed everything forever.

Izuku ran into someone.

More accurately, they ran into  _ him, _ seeing as they were about two feet taller than him and he’d been carrying his toolkit. The inadvertent contact knocked him off his feet, sending him sprawling on the floor with a startled yelp.

The figure immediately stopped, apologetic.

“I’m terribly sorry, young man. I wasn’t looking where I was going.”

Izuku glanced up, shocked into silence at the familiar, distinctive voice.

And saw a tall Trill man, with blond bangs framing his face and vibrant blue eyes, still sharp and keen in his age.

Toshinori, the current host of the Ofa Symbiont and the greatest diplomat to ever come off Trill.

Izuku’s hero.

Izuku wanted to die right there.

He didn't, fortunately. But he sure as hell wanted to.

Many, many stammered apologies and a rather awkward conversation later, Izuku found out that Toshinori was actually residing in the hospital for the time being. And he’d just been placed in the Recovery Wing, where Izuku was working.

Oh boy.

Tsuyu told him he was being silly for crying, but Izuku thought his tears were justified considering he was helping the greatest man he’d ever looked up to, thank you very much.

Tsuyu just laughed at him.

So Izuku went back to work, doing regular maintenance by Toshinori’s (“Please, call me Toshi, my boy. We do see a lot of each other, after all.”) quarters and in the medical bays Tsuyu worked at. 

And to the greatest surprise of his life, Toshi… actually seemed to enjoy his company.

So on his off hours, more often than not, Izuku found himself in the older Trill’s quarters, listening to his stories.

He found out that there had been a bombing in the embassy Toshi had been visiting for negotiations, worried about the possible Dominion threat. They had almost no evidence of who had done it, but many ambassadors had been killed that day.

Toshi had almost been one of them- he’d been pulled out of the rubble with a piece of rebar impaled through his side.

“Lost most of my stomach and part of my lung,” he said thoughtfully, lowering his shirt to hide the mass of scar tissue once more. “Ofa was injured as well… for a while, I was worried they wouldn’t make it. That they would die with me. And…”

He’d hesitated here, almost unwilling to speak.

“I have no proof. But I am certain that I saw an old face at the embassy… before the explosion.”

“Who?” Izuku had whispered, horrified and sympathetic in equal parts.

“It doesn’t matter as much anymore,” was all Toshi said, weary. “The brother symbiont to Ofa was lost at Wolf 359.” 

And that was where the conversation had ended, despite Izuku’s feelings of uneasiness and burning curiosity.

Time passed.

A full year later, Toshi was ready to leave Dagobah Station, and Izuku had just received a new assignment to a ship patrolling the Cardassian border, the USS Thanatos, under Captain Yamada. Tsuyu had the same assignment posting, Starfleet graduates too valuable on the eve of possible war to remain on no-name medical stations in the middle of nowhere. The Otto, a small transport ship, picked the three of them up to take them to Deep Space Nine, where Izuku and Tsuyu would rendezvous with their commanding officer, and Toshi would take part in negotiations taking place on the station.

But, the universe had other plans.

It had been a Klingon Bird of Prey, fresh off the breaking of the Khitomer Accords, and looking for fresh meat.

The Otto barely made it out of there intact.

And in the battle and the confusion…

Toshinori was injured.

Fatally.

It was time for the Ofa Symbiont to take a new host.

“I would have chosen you,” Toshinori insisted, laying on Tsuyu’s medical bed, eyes bright and lucid even through the blood and the pain and the little, little time they had left. “My boy... even if it hadn’t happened this way. I can think of no one better to be my successor.”

“But I was rejected from the Program!” Izuku insisted tearfully, holding onto his mentor’s hand so tightly his spots were almost black against the bloodless white of his skin.

Toshinori just smiled, a shadow of that beaming, calming symbol he was so known for.

“So was I,” he said simply.

Izuku didn’t remember much of the Joining.

Tsuyu, above him, professional and calm even through her fear and uncertainty.

Toshi, beside him.

The lights of the med bay, dimmed almost to black, the red emergency lighting still scattering across the bulkheads.

“Please don’t go,” Izuku found himself whispering, even as the natural anesthetic of the Joining process dulled his thoughts and made his vision fade to black.

“I’m not going anywhere,” he thought he heard the soft rumble of Toshi reply, just before the depths claimed him. “I will  _ always _ be with you.”

Izuku slept.

And when he woke, Toshinori was gone.

What had happened was no one's fault, except for maybe Fate’s. The transfer had had to happen so quickly, and the Symbiont had already been injured once before. It was a miracle and a testament to Tsuyu’s skill that the Joining had gone as well as it had.

But Izuku couldn’t connect to the Symbiont.

“I’m sorry,” Tsuyu said, the dark, exhausted circles under her eyes making her complexion sallow and wan. “I… the Symbiont has partially cut itself off from you. In time, it should be able to be corrected, but…”

Tsuyu didn’t cry often. That was usually Izuku’s job. But there, in the stillness of a med bay that had one person less than before, they simply clung to each other and did their best not to shatter in the awful silence that had been left behind.

In the wake of tragedy and grief, they took their posting on the USS Thanatos, to fall behind enemy lines a few short months later. 

Which is where the story begins, not ends.

Izuku Midoriya is a Trill, and Joined.

The Ofa Symbiont lives in him.


End file.
